Field
This invention relates to a fuel cell module including a fuel cell and a case housing the fuel cell.
Related Art
Some fuel cell including a cell stack as a stack of multiple unit cells is housed in a box-like case and used therein. Application of a load to the cell stack in a stacking direction has been required in order to maintain each of the unit cells in a stacked state inside the case. This may be achieved by a fuel cell suggested for example in JP2013-12325A. In this fuel cell, a pressure plate having an end surface substantially the same in size as an end surface of the cell stack is arranged outside the cell stack in the stacking direction so as to face an inner surface of the case. A load is applied to the cell stack in the stacking direction with the pressure plate. In this fuel cell, the case is provided with an opening and a screw hole penetrating the case in a thickness direction that are formed in advance in the surface of the case facing the pressure plate. After the fuel cell is housed in the case, a given load is applied to the pressure plate with a pressure member inserted through the opening. Then, with the load acting on the pressure plate, a load adjusting screw is screwed in through the screw hole to contact the pressure plate, thereby maintaining a state where the given load acts on the cell stack.
In the aforementioned fuel cell, reactive force from the cell stack against the load is transmitted to the case through the load adjusting screw. This causes a problem of deformation of the case near the screw hole. Additionally, a distance between the pressure plate and the case may become nonuniform due to nonuniformity of the thickness of the unit cell occurring during manufacture and loosening of the screw during operation, for example. This can be controlled by making the load adjusting screw contact the pressure plate by adjusting a degree of screwing of the load adjusting screw. However, depending on the length of the screw hole (screw thread) provided to the case, the length of the load adjusting screw might become insufficient or the rear end of the load adjusting screw might protrude from the case. To avoid such risks, several types of load adjusting screws of different lengths should be prepared as load adjusting screws for maintenance of a fuel cell module, causing increase in operational cost of the fuel cell module. Suppressing increase in installation space for the entire fuel cell module including the case has also been required. As understood from the above, a technique to allow suppression of deformation of the case housing the fuel cell, suppression of increase in operational cost of the fuel cell module, and suppression of increase in size of the entire fuel cell module including the case is desired.